1. Field of the Invention
This invention concerns the dispensing of pasty or viscous products such as toothpastes.
2. The Prior Art
Many proposals have been made for essentially plastic dispensers capable of dispensing toothpaste from a dispensing orifice by repeated operation of a user-engageable portion or member such as a flexible diaphragm portion, a piston, a lever or a knurled wheel. Such dispensers may have various advantages over the squeezable tubes in which toothpastes have traditionally been marketed, and lately have met substantial consumer acceptance because, in particular, of their ease of use (particularly their capagility of one-handed operation), their attractive appearance, and their ability to be stood upright on a shelf. In comparison with the more conventional squeeze tubes, however, these dispensers have been expensive, and their market penetration has been correspondingly limited.
The considerable cost of the existing dispensers can largely be attributed to the considerable number, often ten or more, of components of which they are made; these components must be individually manufactured (by injecting-molding, for example, in the case of a thermoplastic component) and later assembled together, and the cost of the dispenser increases generally in proportion to the number of components of which it is made. Thus, there exists a need for a dispenser for pasty or viscous products which is inherently simple and capable of manufacture from a relatively small number of components, and yet which, by suitable arrangement, may to a greater or lesser degree still possess the advantages of the existing commercially available dispensers. Preferably, for corrosion-resistance, the dispenser should also be capable of manufacture solely from thermoplastic materials.
Product dispensers have been proposed having an elongate deformable tube communicating the dispensing orifice with a collapsible or reduceable- volume reservoir of the product. The dispenser has an actuator arranged to operate upon the outer surface of the tube so as, by repeated forward movements towards the orifice whilst pinching the tube closed, to dispense successive metered amounts of the product by what may be considered as a peristaltic action. After each dispensing stroke the actuator is reset, that is, it is returned to its initial starting condition in preparation for the next dispensing operation. Dispensers of this general kind, hereinafter generally to be referred to for brevity as "peristaltic action dispensers," are described and claimed in British Patent Specification No. 1,387,349, U.S. Pat. No. 3,881,641 and European Patent Publication No. EP. 105771 A1.
As these disclosures indicate, however, the peristaltic action dispensers proposed hitherto have again tended to be of complicated construction with a multiplicity of different components, some of which are of metal; they have been generally unsuited to mass production techniques, and their complicated construction has not been consistent with the compact appearance which is desirable, for example, for toothpaste dispensers of 100 cc capacity and typically having an overall length of 175 mm and a diameter of 36 mm. In fact, it is not belived that any commercial exploitation of peristaltic action dispensers of this type has taken place.